DE1164395B - Process for the preparation of 1, 3-diaryl-5, 5-dialkylbiuretes - Google Patents

Description

Process for the preparation of 1,3-diaryl-5,5-dialkylbiurets 1,3-diaryl-5,5-dialkylbiurets, z. B. the 1,3-diphenyl-5,5-dimethylbiuret, are already from the German patent 1 032 595 known. The products have herbicidal properties, due to which they are valuable herbicides.

According to the information in the cited patent, the preparation of the 1,3-diaryl-5,5-dialkylbiurets is to be carried out analogously to the methods in Houben-Weyl, »Methods of the org. Chemistry ", 4th edition, Vol. VIII, p. 208, or in" Journal of Organic Chemistry ", Vol. 8 (1943), pp. 230 to 238, methods given for 1,3-diaryl-5-monoalkylbiurets take place. Triethylphosphine is added to phenyl isocyanate in accordance with the equation 1,3-Diphenyluretdione (I) formed after recrystallization (for example from dioxane or dibutyl ether) in alcoholic solution with heating with 2 mol of the amine concerned (ie a 100% excess) reacted. The product which crystallizes out of the cooled reaction solution is then filtered off with suction.

In fact, according to the method described, in the first reaction stage Diphenyluretdione can be obtained without difficulty, the yield of recrystallized Intermediate 800 / a of theory is. In the second reaction step of the known Process drops the 1,3-diphenyl-5,5-dimethylbiuret in a yield of 670/0 theory, d. that is, the total yield is 53.60 / 0 of theory (based on on phenyl isocyanate used).

This low yield and the need to use the resulting mother liquors to work up, to recover the solvents and the cumbersome two times Crystallization process leave the known process for the preparation of 1,3-diaryl-5,5-dialkylbiuretas seem unsuitable on an industrial scale. But if you go to at least the Avoid pure preparation of the intermediate in the second reaction stage from raw, d. H. not recrystallized diphenyluretdione, so join the Implementation of the implementation has even greater difficulties: After the known, The above-described processes are then namely in addition to the desired 1,3-diphenyl-5, 1,3-diphenyl-5,5-dimethylbiuret significant amounts of phenyldimethylurea, phenyl urethane and diphenylallophanoic acid esters. From the resulting sticky-oily reaction mixture is because of the low melting point of the same, the separation of the individual components so difficult that despite considerable effort, the desired product only in yields below 500/0 of theory (based on phenyl isocyanate used) can be isolated.

It has now been found that even from diaryluretdione which has not been recrystallized and 1,3-diaryl-5,5-dialkylbiurets when using stoichiometric amounts of the dialkylamine in question in very pure, crystallized form and with a yield of more than 900/0 the theory (based on the aryl isocyanate used) can be obtained if the Reaction in optionally chlorinated hydrocarbons (e.g. toluene, benzene, Chlorobenzene, ligroin, carbon tetrachloride, tetrachloroethane) and also the reaction in the presence of monovalent carboxylic acids (e.g. acetic acid, propionic acid) or using the salts of the respective to be used as starting material Dialkylamines with the acids mentioned. The yields are in this case at 950/0 of theory (based on isocyanate used).

The reaction proceeds so smoothly in the presence of such anions - probably in the sense of the following equation (2) - that they can be carried out with almost quantitative yield even in the presence of water and still obtain a product that crystallizes well and is very pure.

In the aforementioned equation, Ar stands for an optionally z. B. substituted by halogen atoms, alkyl-alkoxy, alkyl mercapto and / or nitro groups Aryl radical, while R, R 'and R "are preferably lower alkyl radicals.

It is by no means when carrying out the method according to the invention necessary to use stoichiometric amounts of said carboxylic acids.

Since the acid in the course of the. Response is constantly being regressed [s. Equation (2)], a fraction of the theoretically required amount is sufficient if the amine is added to the solution or suspension of the uretdione to the extent that free acid is present in the reaction mixture.

Appropriately, a concentrated (preferably 50 to 600 / above) Solution of the aryl isocyanate in a solvent inert to isocyanates (preferably Benzene, toluene or chlorobenzene) with the addition of small catalytically active amounts of a trialkylphosphine (preferably ti-n-butylphosphine) at room temperature several Stirred for hours, the 1,3-diaryluretdione crystallizing out. The latter separates the mother liquor is removed by filtration or centrifugation and washed with it some solvent. While the filtrate and the washing solution as a solvent for Another approach to the production of the uretdione can be used, whereby Overall yields of over 950/0 of theory can be achieved, the solvent-containing one 1,3-diaryluretdione in another reaction vessel according to the invention in a little diluent, z. B. carbon tetrachloride or another optionally chlorinated hydrocarbon, suspended and after adding one of the above-mentioned carboxylic acids (for example 1/3 mole of acetic acid per mole of diaryluretdione) added with the dialkylamine, that the temperature of the mixture is between 20 and 1200C (preferably 35 up to 55 "C).

When the addition of the amine has ended, the reaction mixture is left in Stir cool and separate the crystallized product by filtration or Centrifuge off. The mother liquor is useful as a solvent for further Conversions are used because - often with the second approach - one is almost quantitative Yields of 1,3-diaryl-5,5-dialkylbiuret are obtained.

The inventive method is generally based on the implementation of 1,3-diaryluretdiones (e.g. optionally chlorinated, alkylated, nitrated Diphenyluretdione or 1,3-bisnaphthyluretdione) can be used with dialkylamines.

The following examples provide an overview of what is claimed Procedure.

Example 1 Preparation of the starting material diphenyluretdione A 50 to 600% solution of phenyl isocyanate in benzene or chlorobenzene is added with 0.003 parts by weight of tris-n-butylphosphine and then stir the mixture several times Hours at room temperature. Then the formed crystal slurry is sucked off, covered with a little solvent, then sucked off again and squeezed out. To this Way one obtains a suitable, still solvent-containing, therefore only about 900% diphenyluretdione (melting point of a sample after drying 175 ° C.). The same amount of phenyl isocyanate is added to the mother liquor.

After adding tris-n-butylphosphine, the procedure above is repeated described. In the second approach, the diphenyluretdione is now almost quantitative Amount received.

1,3-Diphenyl-5,5-dimethylbiuret Dissolve 60g (1 mol) of acetic acid in 150ml chlorobenzene and then add 45 to this mixture with external cooling g (1 mole) of dimethylamine. As the temperature of the reaction mixture increases, a solution is formed or

Suspension of dimethylammonium acetate, gradually stirring a suspension of 238 g (1 mol) of diphenyluretdione in 300 ml of chlorobenzene and 20 ml of glacial acetic acid is added. The result is a clear solution, its temperature rises to 50 to 550C. The solvent is then reduced in vacuo (40 to 50 Torr) distilled off; the residue is poured into 700 ml of water and stirred.

290 g (98.30 / 0 of theory) of white granules are obtained which melts at 103 to 105 "C after drying.

In the same way, the reaction described can also be carried out in carbon tetrachloride (instead of chlorobenzene). The yield is in this Trap 265 g (90.5% of theory).

Under the appropriate reaction conditions, bis-14-chlorophenyl) uretdione is converted the 1,3-bis44'-chlorophenyl> 5,5-dimethylbiuret of m.p. 158 to 159 "C was obtained.

Example 2 238 g (1 mol) of diphenyluretdione are dissolved in 300 ml of chlorobenzene, to which 20 ml (1/3 mol) of glacial acetic acid are added, suspended. Add dropwise to this suspension one in the course of 21/2 hours 97 g (about 1 mol) of an aqueous 51, 20% dimethylamine solution, Where at the temperature of the reaction mixture rises to 36 "C. After adding the dimethylamine dropwise and cooling the mixture to room temperature the reaction product precipitates in crystalline form. It is cooled and in vacuo dried at 50 "C.

The yield is 169 g (59.7% of theory); M.p. 103-105 "C.

The mother liquor is decanted from the water, with 165 g (0.7 mol) Diphenyluretdione added and, as described above, with 69 g of a 51, 20 / oigen brought to reaction aqueous dimethylamine solution. 178 g of 1,3-diphenyl-5,5-dimethylbiuret fall (90.30 / 0 of theory) from m.p. 105 ° C.

The filtrate can be used in the same way for a new approach will. But if it is concentrated in vacuo (70 torr), 116 g of 1,3-diphenyl-5,5-dimethylbiuret are obtained from m.p. 101 to 105 "C.

This corresponds to a total yield of 463 g (970/0 of theory).

The reaction described can be carried out in an analogous manner with propionic acid be carried out, with a product of melting point 106 to 108 "C received.

Claims: 1. Process for the preparation of 1,3-diaryl-5, 5-dialkylbiuretas from diaryluretdiones and dialkylamines, d a d u r c h g e k e n n -z e i c h n e t that the amines in the form of their carbonic acid salts in solutions or suspensions lets act of 1,3-diaryluretdione.

Claims (1)

2. The method according to claim 1, characterized in that the Diaryluretdiones suspended in solvents or in the presence of carboxylic acids dissolves and then adds the free amines to the reaction mixture. 3. The method according to claim 1 and 2, characterized in that one optionally chlorinated, aliphatic or aromatic hydrocarbons as solvents used. 4. The method according to claim 1, 2 and 3, characterized in that the reaction is carried out in carbon tetrachloride or tetrachloroethane. ~~~~~~~~ References considered: Chemical Reviews, 65 (1956), p. 131.